to recap, there are three key subsystems making up the heart of the quencher.
1 of 3 = selective absorber: there are many sources in India that make selective absorbers. I found one in Bangalore that can work with Aluminium (and not just copper = expensive), using a ‘black chrome’ coating with a guaranteed 30 year operational lifetime
2 of 3 = custom heat pipe: there is a vendor in Pune, Maharashtra, that supplies heat pipes into the solar thermal water heating market, who can also make custom heat pipes.
3 of 3 = evaporator-condenser: We need to get started on a detailed design on this part of the system.
Any volunteers?;) Perhaps a mechanical engineer who has worked with HVAC systems, or automotive radiators, or pressure vessels?